Which health messages work?

IMAGE: Is it better to be positive or negative? Many of the most vivid public health appeals have been negative -- 'Smoking Kills' or 'Drive, Drive, and Die' -- but...
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Credit: Daniel Miller

Is it better to be positive or negative? Many of the most vivid public health appeals have been negative - "Smoking Kills" or "Drink, Drive, and Die" - but do these negative messages work when it comes to changing eating behavior?

Past literature reviews of positive- or gain-framed versus negative or loss-based health messages have been inconsistent. In our content analysis of 63 nutrition education studies, we discovered four key questions which can resolve these inconsistencies and help predict which type of health message will work best for a particular target audience: 1. Is the Target Audience Highly Involved in this Issue? 2. Is the Target Audience Detail-oriented? 3. Is the Target Audience Risk Averse? 4. Is the Outcome Uncertain? The more questions are answered with a "Yes," the more a negative- or loss-based health message will be effective. Let's look at these in more detail.

1. Is the Target Audience Highly Involved in this Issue? The more knowledgeable or involved a target audience, the more strongly they'll be motivated by a negative- or loss-based message. In contrast, those who are less involved may not believe the message or may simply wish to avoid bad news. These less involved consumers generally respond better to positive messages that provide a clear, actionable step that leaves them feeling positive and motivated. For instance, telling them to "eat more sweet potatoes to help your skin look younger" is more effective than telling them "your skin will age faster if you don't eat sweet potatoes. The former doesn't require them to know why or to link sweet potatoes to Vitamin A.

2. Is the Target Audience Detail-oriented? People who like details - such as most of the people designing public health messages - prefer negative- or loss-framed messages. They have a deeper understanding and knowledge base on which to elaborate on the message. In her coverage of the article for the Food Navigator, Elizabeth Crawford, noted that most of the general public is not interested in the details and is more influenced by the more superficial features of the message, including whether it is more positive or attractive relative to the other things vying for their attention at that moment.

3. Is the Target Audience Risk Averse? When a positive outcome is certain, gain-framed messages work best ("you'll live 7 years longer if you are a healthy weight"). When a negative outcome is certain, loss-framed messages work best ("you'll die 7 years earlier if you are obese"). For instance, we found that if it is believed that eating more fruits and vegetables leads to lower obesity, a positive message ("eat broccoli and live longer") is more effective than a negative message.

4. Is the Outcome Uncertain? When claims appear factual and convincing, positive messages tend to work best. If a person believes that eating soy will extend their life by reducing their risk of heart disease, a positive message stating this is best. If they aren't as convinced, a more effective message could be "people who don't eat soy have a higher rate of heart disease."

These findings show how those who design health messages, such as health care professionals, will be impacted by them differently than the general public. When writing a health message, rather than appealing to the sentiment of the experts, the message will be more effective if it's presented positively. The general public is more likely to adopt the behavior being promoted if they see that there is a potential positive outcome. Evoking fear may seem like a good way to get your message across but this study shows that, in fact, the opposite is true--telling the public that a behavior will help them be healthier and happier is actually more effective.

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By Brian Wansink, PhD, author of Slim by Design.

Director of the Cornell Food and Brand Lab

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